check-ip-change

#!/bin/bash 

# This script uses curl and amazon web services (checkip.amazonaws.com)
# to detect changes in the user's IP-address.
# Whenever such a change occurrs, the old and new
# ip are printed on separate lines.

IPPATH="$HOME/.ip"

if [[ -a $IPPATH ]]; then
    old=$(< $IPPATH)
else
    old=""
fi

new=$(curl -s checkip.amazonaws.com)

if [[ "$old" != "$new" ]]; then
    echo "$new" > $IPPATH
    echo $old
    echo $new
fi